When EPA first opened its doors in 1970, the agency had weak authority to protect U.S. waters, lacking the legal power to write effluent guidelines and possessing only general authority to require secondary treatment from industrial dischargers. [1]

Technically, the name of the law is the Federal Water Pollution Control Act.[2] The first FWPCA was enacted in 1948, but took on its modern form when completely rewritten in 1972 in an act entitled the Federal Water Pollution Control Act Amendments of 1972.[3] Major changes have subsequently been introduced via amendatory legislation including the Clean Water Act of 1977[4] and the Water Quality Act of 1987.[5]

All waters with a "significant nexus" to "navigable waters" are covered under the CWA; however, the phrase "significant nexus" remains open to judicial interpretation and considerable controversy. The 1972 statute frequently uses the term "navigable waters," but also defines the term as "waters of the United States, including the territorial seas."[6] Some regulations interpreting the 1972 law have included water features such as intermittent streams, playa lakes, prairie potholes, sloughs and wetlands as "waters of the United States." In the 2006 case Rapanos v. United States, a plurality of the Supreme Court held that the term "waters of the United States":

...includes only those relatively permanent, standing or continuously flowing bodies of water "forming geographic features" that are described in ordinary parlance as "streams[,] ... oceans, rivers, [and] lakes.

Point sources may not discharge pollutants to surface waters without a permit from the National Pollutant Discharge Elimination System (NPDES). This system is managed by the United States Environmental Protection Agency (EPA) in partnership with state environmental agencies. EPA has authorized 46 states to issue permits directly to the discharging facilities. The CWA also allows tribes to issue permits, but no tribes have been authorized by EPA. In the remaining states and territories, the permits are issued by an EPA regional office. [9] (See Titles III and IV.)

In previous legislation, Congress had authorized states to develop water quality standards, which would limit discharges from facilities based on the characteristics of individual water bodies. However, these standards were only to be developed for interstate waters, and the science to support this process (i.e. data, methodology) was in the early stages of development. This system was not effective and there was no permit system in place to enforce the requirements. In the 1972 CWA Congress added the permit system and a requirement for technology-based effluent limitations.[10]

The 1972 CWA created a new requirement for technology-based standards for point source discharges. EPA develops these standards for categories of dischargers, based on the performance of pollution control technologies without regard to the conditions of a particular receiving water body. The intent of Congress was to create a "level playing field" by establishing a basic national discharge standard for all facilities within a category, using a "Best Available Technology." The standard becomes the minimum regulatory requirement in a permit. If the national standard is not sufficiently protective at a particular location, then water quality standards may be employed.[11]

The 1972 act authorized continued use of the water quality-based approach, but in coordination with the technology-based standards. After application of technology-based standards to a permit, if water quality is still impaired for the particular water body, then the permit agency (state or EPA) may add water quality-based limitations to that permit. The additional limitations are to be more stringent than the technology-based limitations and would require the permittee to install additional controls. Water quality standards consist of four basic elements: 1) Designated uses; 2) Water quality criteria; 3) Antidegradation policy and 4) General policies.[12]

According to water quality standard regulations, states and Indian tribes are required to specify appropriate water uses. Identification of appropriate water uses takes into consideration the usage and value of public water supply, protection of fish, wildlife, recreational waters, agricultural, industrial and navigational water ways. Suitability of a water body is examined by states and tribes for usages based on physical, chemical, and biological characteristics. States and Indian tribes also examine geographical settings, scenic qualities and economic considerations to determine fitness of designated uses for a water bodies. If these standards indicate designated uses to be less than those presently attained, states or tribes are required to revise standards to reflect the uses actually being attained. For any body of water with designated uses that do not include “fishable/swimmable” target use that is identified in section 101(a)(2) of CWA, a Use Attainability Analysis must be conducted. Every three years, such bodies of water must be reexamined in order to verify if new information is available that demand a revision of the standard. If new information is available that specify “fishable/swimmable” uses can be attained, then the use must be designated.[12]

States and tribes protect designated areas by adopting water quality criteria that allow them to adopt the criteria that EPA publishes under §304(a) of the CWA, modify the §304(a) criteria to reflect site-specific conditions or adopt criteria based on other scientifically defensible methods. Water quality criteria can be numeric criteria that toxicity causes are known for protection against pollutants. A narrative criterion is water quality criteria which serves as basis for limiting toxicity of waste discharge to aquatic species. A biological criterion is based on aquatic community which describes the number and types of species in a water body. A nutrient criterion solely protects against nutrient over enrichment; and a sediment criterion describes conditions of contaminated and uncontaminated sediments in order to avoid undesirable effects.[12]

Water quality standards consist of an anti-degradation policy that requires states and tribes to establish a three-tiered anti-degradation program. Anti-degradation procedures identify steps and questions that need to be addressed when specific activities affect water quality. Tier 1 is applicable to all surface waters. It maintains and protects current uses and water quality conditions to support existing uses. Current uses are identified by showing that fishing, swimming, and other water uses have occurred and are suitable since November 28, 1975. Tier 2 maintains and protects water bodies with existing conditions that are better to support CWA 101(a)(2) "fishable/swimmable" uses. Tier 3 maintains and protects water quality in outstanding national resource waters (ONRWs), which are the highest quality waters in the US with ecological significance.[12]

States and Indian tribes adopt general policies pertaining to water quality standards that are subject to review and approval by the EPA. These provision regarding water quality standards include mixing zones, variance, and low flow policies. Mixing zone policy is defined area surrounding a point source discharge where sewage is diluted by water. Methodology of mixing zone procedure determines the location, size, shape and quality of mixing zones. Variance policy temporarily relax water quality standard and are alternatives to removing a designated use. States and tribes may include variance as part of their water quality standard. Variance is subject to public review every three years and warrant development towards improvement of water quality. Low Flow policy pertains to states and tribes water quality standards that identify procedures applied to determining critical low flow conditions.[12]

Nonpoint source pollutants, such as sediments, nutrients, pesticides, herbicides, fertilizers,animal wastes and other substances that enter our water supply as components of runoff and ground water, have increased in relative significance and accounts for more than 50 percent of the pollution in U.S. waters.[13]

Congress exempted some water pollution sources from the point source definition in the 1972 CWA, and was unclear on the status of some other sources. These sources were therefore considered to be nonpoint sources that were not subject to the permit program.

Stormwaterrunoff from industrial sources, municipal storm drains, and other sources were not specifically addressed in the 1972 law. EPA declined to include urban runoff and industrial stormwater discharges in the NPDES program and consequently was sued by an environmental group. The courts ruled that stormwater discharges must be covered by the permit program.[15]

A growing body of water research during the late 1970s and 1980s indicated that stormwater runoff was a significant cause of water quality impairment in many parts of the U.S. In the early 1980s EPA conducted the Nationwide Urban Runoff Program (NURP) to document the extent of the urban stormwater problem. The agency began to develop regulations for stormwater permit coverage, but encountered resistance from industry and municipalities, and there were additional rounds of litigation. This litigation was pending when Congress considered further amendments to the Act in 1986.

In the Water Quality Act of 1987 (1987 WQA) Congress responded to the stormwater problem by requiring that industrial stormwater dischargers and municipal separate storm sewer systems (often called "MS4") obtain NPDES permits, by specific deadlines. The permit exemption for agricultural discharges continued, but Congress created a nonpoint source pollution demonstration grant program at EPA to expand the research and development of nonpoint controls and management practices.

To combat nonpoint source pollution, EPA initiated numerous programs and grants to aid the public in improving their local water quality. These programs are described at an EPA website, Watershed Central.

Congress created a major public works financing program for municipal sewage treatment in the 1972 CWA. A system of grants for construction of municipal sewage treatment plants was authorized and funded in Title II. In the initial program the federal portion of each grant was up to 75 percent of a facility's capital cost, with the remainder financed by the state. In subsequent amendments Congress reduced the federal proportion of the grants and in the 1987 WQA transitioned to a revolving loan program in Title VI. Industrial and other private facilities are required to finance their own treatment improvements on the "polluter pays" principle.

Title I includes a Declaration of Goals and Policy[16] and various grant authorizations for research programs and pollution control programs. Some of the programs authorized by the 1972 law are ongoing (e.g. section 104 research programs, section 106 pollution control programs, section 117 Chesapeake Bay Program) while other programs no longer receive funds from Congress and have been discontinued.

Categorical Pretreatment Standards are issued to industrial users (also called "indirect dischargers") contributing wastes to POTW.[20] These standards are developed in conjunction with the effluent guidelines program. As with effluent guidelines and NSPS, pretreatment standards consists of Pretreatment Standards for Existing Sources (PSES) and Pretreatment Standards for New Sources (PSNS). There are 27 categories with pretreatment standards as of 2011.

To date, the effluent guidelines and categorical pretreatment standards regulations have been published for 56 categories and apply to between 35,000 and 45,000 facilities that discharge directly to the nation's waters. These regulations are responsible for preventing the discharge of almost 700 billion pounds of pollutants each year.[21] EPA has updated some categories since their initial promulgation and has added new categories.

The secondary treatment standards for POTWs and the effluent guidelines are implemented through NPDES permits. (See Title IV.) The categorical pretreatment standards are typically implemented by POTWs through permits that they issue to their industrial users.[22]

Water quality standards (WQS) are risk-based requirements which set site-specific allowable pollutant levels for individual water bodies, such as rivers, lakes, streams and wetlands. States set WQS by designating uses for the water body (e.g., recreation, water supply, aquatic life, agriculture) and applying water quality criteria (numeric pollutant concentrations and narrative requirements) to protect the designated uses. An antidegradation policy is also issued by each state to maintain and protect existing uses and high quality waters.[23]

Water bodies that do not meet applicable water quality standards with technology-based controls alone are placed on the section 303(d) list of water bodies not meeting standards. Water bodies on the 303(d) list require development of a Total Maximum Daily Load (TMDL). A TMDL is a calculation of the maximum amount of a pollutant that a water body can receive and still meet WQS. The TMDL is determined after study of the specific properties of the water body and the pollutant sources that contribute to the non-compliant status. Generally, the TMDL determines load based on a Waste Load Allocation (WLA), Load Allocation (LA), and Margin of Safety (MOS) Once the TMDL assessment is completed and the maximum pollutant loading capacity defined, an implementation plan is developed that outlines the measures needed to reduce pollutant loading to the non-compliant water body, and bring it into compliance. Over 60,000 TMDLs are proposed or in development for U.S. waters in the next decade and a half.

Following the issuance of a TMDL for a water body, implementation of the requirements involves modification to NPDES permits for facilities discharging to the water body to meet the WLA allocated to the water body (see Title IV).

As of 2007, approximately half of the rivers, lakes, and bays under EPA oversight were not safe enough for fishing and swimming.[24] The development of WQS and TMDL is a complex process, both scientifically and legally, and it is a resource-intensive process for state agencies.

The primary mode of informing the quality of water of rivers, lakes, streams, ponds, estuaries, coastal waters and wetlands of the U.S. is through the National Water Quality Inventory Report. Water quality assessments are conducted pursuant to water quality standards adopted by states and other jurisdictions (territories, interstate commissions and tribes). The report is conveyed to Congress as a means to inform Congress and the public of compliance with quality standards established by states, territories and tribes.[25][26] The assessments identify water quality problems within the states and jurisdictions, list the impaired and threatened water bodies, and identify non-point sources that contribute to poor water quality. Every two years states must submit reports that describe water quality conditions to EPA with a complete inquiry of social and economic costs and benefits of achieving goals of the Act. The report is organized into two major sections; Section 1 shows national assessment of each type of water body, with causes and sources identified. Section 2 summarizes recommendations on improvement of water resource management.[25]

Under section 309, EPA can issue administrative orders against violators, and seek civil or criminal penalties when necessary.[27]

For a first offense of criminal negligence, the minimum fine is $2,500, with a maximum of $25,000 fine per day of violation. A violator may also receive up to a year in jail. On a second offense, a maximum fine of $50,000 per day may be issued.

For a knowing endangerment violation, i.e. placing another person in imminent danger of death or serious bodily injury, a fine may be issued up to $250,000 and/or imprisonment up to 15 years for an individual, or up to $1,000,000 for an organization.

States that are authorized by EPA to administer the NPDES program must have authority to enforce permit requirements under their respective state laws.

The 1987 amendments created the Nonpoint Source Management Program under CWA section 319.[30] This program provides grants to states, territories and Indian tribes to support demonstration projects, technology transfer, education, training, technical assistance and related activities designed to reduce nonpoint source pollution. Grant funding for the program averaged $210 million annually for Fiscal Years 2004 through 2008.[31]

The NPDES permits program is authorized by CWA section 402.[33] The initial permits issued in the 1970s and early 1980s focused on POTWs and industrial wastewater—typically "process" wastewater and cooling water where applicable, and in some cases, industrial stormwater. The 1987 WQA expanded the program to cover stormwater discharges explicitly, both from municipal separate storm sewer systems (MS4) and industrial sources.[34] The MS4 NPDES permits require regulated municipalities to use Best Management Practices to reduce pollutants to the "Maximum Extent Practicable."

Non-stormwater permits typically include numeric effluent limitations for specific pollutants. A numeric limitation quantifies the maximum pollutant load or concentration allowed in the discharge, e.g., 30 mg/L of biochemical oxygen demand. Exceeding a numeric limitation constitutes a violation of the permit, and the discharger is subject to fines as laid out in section 309. Facilities must periodically monitor their effluent (i.e., collect and analyze wastewater samples), and submit Discharge Monitoring Reports to the appropriate agency, to demonstrate compliance. Stormwater permits typically require facilities to prepare a Stormwater Pollution Prevention Plan and implement best management practices, but do not specify numeric effluent limits and may not include regular monitoring requirements. Some permits cover both stormwater and non-stormwater discharges. NPDES permits must be reissued every five years. Permit agencies (EPA, states, tribes) must provide notice to the public of pending permits and provide an opportunity for public comment.[35]

As of 2001, over 400,000 facilities were subject to NPDES permit requirements.[36] This number includes permanent facilities such as municipal (POTW, MS4) and industrial plants, and construction sites, which are temporary stormwater dischargers.[37]

After passage of the CWA in 1972, a controversy arose as to its application to agriculture and certain other activities. The Act was interpreted by some to place restrictions on virtually all placement of dredged materials in wetlands and other waters of the United States, raising concern that the federal government was about to place all agricultural activities under the jurisdiction of the U.S. Army Corps of Engineers (USACE). For opponents of the Act, section 404 had, as a result of this concern, become a symbol of dramatic over-regulation.[38]:901–903 When Congress considered the 1977 CWA Amendments, a significant issue was to ensure that certain agricultural activities and other selected activities, could continue without the government’s supervision—in other words, completely outside the regulatory or permit jurisdiction of any federal agency.

The 1977 amendments included a set of six section 404 exemptions. For example, totally new activities such as construction of farm roads, Sec. 1344(f)(1)(E), construction of farm or stock ponds or irrigation ditches, and minor agricultural drainage, Sec. 1344(f)(1)(A), all are exempted by Statute. Section 1344(f)(1)(C), which exempts discharge of dredged material “for the purpose of. . . the maintenance of drainage ditches.” All of these exemptions were envisioned to be self-executing, that is not technically requiring an administrative no-jurisdiction determination. One such example was the maintenance of agricultural drainage ditches.[38]:906 Throughout the hearing process, Congressmen of every environmental persuasion repeatedly stated that the over $5 Billion invested in drainage facilities could be maintained without government regulation of any kind.[38]:906–912 Senator Edmund Muskie, for example, explained that exempt activities such as agricultural drainage would be entirely unregulated.[38]:949 Other exemptions were granted as well, including exemptions for normal farming activities.

Although Congress envisioned a set of self-executing exemptions, it has become common for landowners to seek no-jurisdiction determinations from the USACE. A landowner who intends to make substantial investments in acquisition or improvement of land might lawfully proceed with exempt activity, a permit not being required. The problem is that if the landowner's assumptions were incorrect and the activity later determined not to be exempt, the USACE will issue a cease and desist order. Obtaining an advanced ruling provides some level of comfort that the activities will have been deemed conducted in good faith.

Because some of the six exemptions involved new activities, such as minor drainage and silviculture (the clearing of forests by the timber industry), Congress recognized the need to impose some limitations on exemptions. Consequently, Congress placed the so-called recapture clause limitation on these new project exemptions. Under section 404(f)(2), such new projects would be deprived of their exemption if all of the following three characteristics could be shown:

A discharge of dredge or fill material in the navigable waters of the United States;

The discharge is incidental to an activity having as its purpose the bringing of an area of navigable waters into a use to which it was not previously subject, and

Where the flow or circulation of navigable waters may be impaired or the reach of such waters may be reduced.

To remove the exemption, all of these requirements must be fulfilled—the discharge, the project purpose of bringing an area into a use to which it was not previously subject, and the impairment or reduction of navigable waters.

Dredge and fill permits (wetlands, lakes, streams, rivers, and other waters of the U.S.)[edit]

Under sections 301 and 502 of the Clean Water Act,[39] any discharge of dredged or fill materials into "waters of the United States," including wetlands, is forbidden unless authorized by a permit issued by the USACE pursuant to section 404.[40] Essentially, all discharges of fill or dredged material affecting the bottom elevation of a jurisdictional water of the U.S. require a Department of the Army (DA) permit from USACE. These permits are an essential part of protecting streams and wetlands, which are often filled by land developers. Wetlands are vital to the ecosystem in filtering streams and rivers and providing habitat for wildlife.[41]

Mountaintop removal mining requires a section 404 permit when soil and rock from the mining operation is placed in streams and wetlands (commonly called a "valley fill"). Pollutant discharges from valley fills to streams also requires an NPDES permit.[42]

There are two main types of wetlands permits: general permits and individual permits. General permits change periodically and cover broad categories of activities, and require the permittee to comply with all stated conditions. General permits (such as the Nationwide Permits) are issued for fill activities that will result in minimal adverse effects to the environment. Individual permits are utilized for actions that are not addressed by a general permit, or that do not meet the conditions of a General Permit. In addition, individual permits typically require more analysis than do the general permits, and usually require much more time to prepare the application and to process the permit.

When the USACE processes an application for an Individual Permit, it must publish/issue a public notice describing the proposed action described in the permit application. Although the Corps District Engineer makes the decision to grant a permit, the USEPA Administrator may veto a permit if it is not reasonable. Before making such a decision, however, USEPA must consult with the USACE. A DA permit typically expires after five years.

The 1987 WQA created a program for management of biosolids (sludge) generated by POTWs.[43] The Act instructed EPA to develop guidelines for usage and disposal of sewage sludge or biosolids. The EPA regulations: (1) Identify uses for sewage sludge, including disposal; (2) Specify factors to be taken into account in determining the measures and practices applicable to each such use or disposal (including publication of information on costs); and (3) Identify concentrations of pollutants which interfere with each such use or disposal. EPA created an Intra-Agency Sludge Task Force to aid in developing comprehensive sludge regulations that are designed to do the following: (1) Conduct a multimedia examination of sewage sludge management, focusing on sewage sludge generated by POTWs; and (2) develop a cohesive Agency policy on sewage sludge management, designed to guide the Agency in implementing sewage sludge regulatory and management programs.[44]

The term biosolids is used to differentiate treated sewage sludge that can be beneficially recycled. Environmental advantages of sewage sludge consist of, application of sludge to land due to its soil condition properties and nutrient content. Advantages also extend to reduction in adverse health effects of incineration, decreased chemical fertilizer dependency, diminishing greenhouse gas emissions deriving from incineration and reduction in incineration fuel and energy costs. Beneficial reuse of sewage sludge is supported in EPA policies: the 1984 Beneficial Reuse Policy and the 1991 Inter-agency Policy on Beneficial Use of Sewage Sludge, with an objective to reduce volumes of waste generated. Sewage sludge contains nutrients such as nitrogen and phosphorus but also contains significant numbers of pathogens such as bacteria, viruses, protozoa and eggs of parasitic worms. Sludge also contains more than trace amounts of organic and inorganic chemicals. Benefits of reusing sewage sludge from use of organic and nutrient content in biosolids is valuable source in improving marginal lands and serving as supplements to fertilizers and soil conditioners. Extension of benefits of sludge on agriculture commodities include increase forest productivity, accelerated tree growth, re-vegetation of forest land previously devastated by natural disasters or construction activities. Also, sewage sludge use to aid growth of final vegetative cap for municipal solid waste landfills is enormously beneficial. Opposing benefits of sludge water result from high levels of pathogenic organisms that can possibly contaminate soil, water, crops, livestock, and fish. Pathogens, metals, organic chemical content and odors are cause of major health, environmental and aesthetic factors. Sludge treatment processes reduce the level of pathogens which becomes important when applying sludge to land as well as distributing and marketing it. Pollutants of sewage sludge come from domestic wastewater, discharge of industrial wastewater, municipal sewers and also from runoffs from parking lots, lawns and fields that were applied fertilizers, pesticides and insecticides.[44]

The quality of sewage sludge is controlled under section 405(d), where limitations are set with methods of use or disposal for pollutants in sludge. EPA, under section 405(d)(3), established a containment approach to limit pollutants instead of numerical limitations. This methodology is more reasonable than numerical limitations and includes design standards, equipment standards, management practice, and operational standards or combination of these. Limits on sewage sludge quality allows treatment works that generate less contaminated pollutants and those that do not meet the sludge quality standards for use and disposal practice must clean up influent, improve sewage sludge treatment and/or select another use of disposal method. EPA has set standards for appropriate practices of use and disposal of biosolids in order to protect public health and the environment, but choice of use or disposal practices are reserved to local communities. Listed under section 405(e) of CWA, local communities are encouraged to use their sewage sludge for its beneficial properties instead of disposing it.[44]

Standards are set for sewage sludge generated or treated by publicly owned and privately owned treatment works that treat domestic sewage and municipal wastewater. Materials flushed in household drains through sinks, toilets and tubs are referred to as domestic wastewater and include components of soaps, shampoos, human excrement, tissues, food particles, pesticides, hazardous waste, oil and grease. These domestic wastewaters are treated at the source in septic tanks, cesspools, portable toilets, or in publicly/privately owned wastewater treatment works. Alternately, municipal wastewater treatments consist of more levels of treatment that provide greater wastewater cleanup with larger amounts of sewage sludge. Primary municipal treatment remove solids that settle at the bottom, generating more than 3,000 liters of sludge per million liters of wastewater that is treated. Primary sludge water content is easily reduced by thickening or removing water and contains up to 7% solids. Secondary municipal treatment process produces sewage sludge that is generated by biological treatment processes that include activated sludge systems, trickling filters, and other attached growth systems. Microbes are used to break down and convert organic substances in wastewater to microbial residue in biological treatment processes. This process removes up to 90% of organic matter and produces sludge that contains up to 2% solids and has increased generated volumes of sludge. Methods of use and disposal of sewage sludge include the following: Application of sludge to agricultural and non-agricultural lands; sale or give-away of sludge for use in home gardens; disposal of sludge in municipal landfills, sludge-only landfills, surface disposal sites and incineration of sludge. Managing quality of sewage sludge not only involves wastewater reduction and separation of contaminated waste from non-contaminants but also pretreatment of non-domestic wastewater. Pretreatment does not thoroughly reduce pollutants level and therefore communities have to dispose rather than use sludge.[44]

Any U.S. citizen may file a citizen suit against any person who has allegedly violated an effluent limitation regulation or against the EPA Administrator if the EPA Administrator failed to perform any non-discretionary act or duty required by the CWA.[45]

The Clean Water State Revolving Fund (CWSRF) program was authorized by the 1987 WQA.[47] This replaced the municipal construction grants program, which was authorized in the 1972 law under Title II. In the CWSRF, federal funds are provided to the states and Puerto Rico to capitalize their respective revolving funds, which are used to provide financial assistance (loans or grants) to local governments for wastewater treatment, nonpoint source pollution control and estuary protection.

The fund provides loans to municipalities at lower-than-market rates. As of 2009 the average rate was 2.3 percent nationwide, compared to an average market rate of 5 percent. In 2009, CWSRF assistance totaling $5.2 billion was provided to 1,971 local projects across the country.[48]

During the 1880s and 1890s, Congress directed USACE to prevent dumping and filling in the nation's harbors, and the program was vigorously enforced.[49] Congress first addressed water pollution issues in the Rivers and Harbors Act of 1899,[50] giving the Corps the authority to regulate most kinds of obstructions to navigation, including hazards resulting from effluents. Portions of this law remain in effect, including Section 13, the so-called Refuse Act. In 1910, USACE used the act to object to a proposed sewer in New York City, but a court ruled that pollution control was a matter left to the states alone. Speaking to the 1911 National Rivers and Harbors Congress, the chief of the Corps, Brigadier General William H. Bixby, suggested that modern treatment facilities and prohibitions on dumping "should either be made compulsory or at least encouraged everywhere in the United States."[49]

Some sections of the 1899 act have been superseded by various amendments, including the 1972 CWA, while other notable legislative predecessors include:

Oil Pollution Act of 1924 prohibited the intentional discharge of fuel oil into tidal waters[52] and provided authorization for USACE to apprehend violators. This was repealed by the 1972 CWA, reducing the Corps' role in pollution control to the discharge of dredged or fill material.[49][53]

Federal Water Pollution Control Act of 1948 created a comprehensive set of water quality programs that also provided some financing for state and local governments. Enforcement was limited to interstate waters. The Public Health Service provided financial and technical assistance.[54]

Water Quality Act of 1965 required states to issue water quality standards for interstate waters, and authorized the newly created Federal Water Pollution Control Administration to set standards where states failed to do so.[55]

Edward Hanousek, Jr v. United States (9th Cir. Court of Appeals, 1996; certiorari denied, 2000). In 1994, during rock removal operations, a backhoe operator accidentally struck a petroleum pipeline near the railroad tracks. The operator’s mistake caused the pipeline to rupture and spill between 1,000 and 5,000 gallons of heating oil into the Skagway river. Despite not being present at the scene during operations White Pass and Yukon Route Roadmaster Edward Hanousek, Jr. and President Paul Taylor were both held responsible for the spill and convicted.[57][58]

Rapanos v. United States (2006). The Supreme Court questioned federal jurisdiction as it attempted to define the Act's use of the terms "navigable waters" and "waters of the United States." The Court rejected the position of the USACE that its authority over water was essentially limitless. Though the case resulted in no binding case law, the Court suggested a narrowing of federal jurisdiction and implied the federal government needed a more substantial link between navigable federal waters and wetlands than it had been using, but held onto the "significant nexus" test.[61][62]

National Cotton Council v. EPA (6th Cir. Court of Appeals, 2009). Point source discharges of biological pesticides, and chemical pesticides that leave a residue, into waters of the U.S. are subject to NPDES permit requirements.[63][64]

Army Corps of Engineers v. Hawkes Co. 578 U.S. (2016), 8-0 ruling that a jurisdictional determination by the Army Corps of Engineers that land contains "waters of the United States" is a "final agency action", which is reviewable by the courts. This allows landowners to sue in court if the Army Corps of Engineers determines that the land contains waters of the United States (and therefore falls under the Clean Water Act).

Rep. David Joyce introduced H.R. 223, the "Great Lakes Restoration Initiative Act of 2015," on January 8, 2015, to carry out restoration programs and projects for the Great Lakes, including toxic substances remediation, controlling invasive species and mitigating nonpoint source pollution.

Rep. Lois Capps introduced H.R. 1278, the "Water Infrastructure Resiliency and Sustainability Act of 2015," on March 4, 2015, to improve aging water infrastructure in local communities. Senator Benjamin Cardin introduced a companion bill in the Senate, S. 741, on March 16, 2015.

In May 2015 the EPA released a new rule on the definition of "waters of the United States" and the future enforcement of the act.[65][66] Thirteen states sued, and on August 27 U.S. Chief District Judge Ralph R. Erickson issued an injunction blocking the regulation in those states.[67] In a separate lawsuit, on October 9 a divided federal appeals court stayed the rule’s application nationwide.[68] Congress then passed a joint resolution under the Congressional Review Act simply overturning the WOTUS rule,[69] but President Obama vetoed the measure.[70]